Capturing a HAR Trace

This article provides step-by-step instructions on how to capture a HAR trace for troubleshooting purposes.

Details

A .har file (or HTTP Archive format) is used to log a web browser’s interaction with a site and to export detailed performance data about web pages it loads. This article outlines the process to capture the file.

Internet Explorer / Edge

For Internet Explorer, Windows 10 allows capturing HAR natively. (IE on Win 7 exports only to XML/CSV. Fiddler– a free download – can be used to import the XML file when needed.)

Open the Network tool in F12 developer tools

Press Record (should see Red Square when it’s recording)

Reproduce the issue

Save button to Export as HAR

Chrome

You can record your HTTP session using the Network tab in the Developer Tools in Chrome. Open the Developer Tools from the menu (Menu > Tools > developer tools), or by pressing Ctrl+Shift+C on your keyboard.

Click on the Network tab

Look for a round button at the top left of the Network tab. Make sure it is red. If it is grey, click it once to start recording.

Check the box next to Preserve log.

You can use the clear button (a circle with a diagonal line through it) right before trying to reproduce the issue to remove unnecessary header information

Save the capture by right-clicking on the grid and choosing "Save as HAR with Content"

Firefox

Starting with Firefox 41, HAR files can be created without any additional extension.